Immune Checkpoint Inhibitor-Induced Adrenalitis and Primary Adrenal Insufficiency: Systematic Review and Optimal Management

Objective Immune checkpoint inhibitors (ICIs) targeting cytotoxic T-lymphocyte antigen 4 or programmed death 1 and its ligand (programmed death ligand 1) have been approved for the treatment of a variety of cancers. However, ICI therapy is associated with a risk of immune-related adverse events. In this study, we reviewed reported cases of adrenalitis and primary adrenal insufficiency (PAI)—rare but lethal endocrine immune-related adverse events—in patients who underwent ICI therapy. Methods We searched multiple databases (PubMed, Web of Science, Cochrane, and Scopus) up to February 2020 for case reports on adrenalitis and PAI caused by ICIs. Results We identified 15 case reports on ICI-induced adrenalitis and PAI and reviewed their clinical presentation, characteristics, immunologic and imaging features, and treatment. We also developed a screening strategy for PAI in patients treated with ICIs. Conclusion Given the morbidity and mortality associated with acute adrenal crisis, physicians—especially endocrinologists and oncologists—should be aware of this particular risk. PAI caused by autoimmune adrenalitis predominantly occurs in patients treated with programmed death 1 inhibitor monotherapy. PAI often coexists with other endocrinopathies and requires mineralocorticoid as well as glucocorticoid replacement. Even after withdrawal of ICIs, PAI can persist and requires lifelong replacement therapy.